There are known and presently used numerous spring structures for the seats of vehicles and furniture. Most of these spring structures are somewhat complex arrangements thought to be necessary in order to provide the desired comfort and support. Examples of such spring structures are shown in Santillo, U.S. Pat. No. 3,156,460 and Crahan, U.S. Pat. No. 2,788,844. Although these spring structures do provide both support and comfort, they obviously require a number of components and are relatively costly to manufacture. These spring structures were designed to provide better comfort and support than could be provided by the more simple spring structures such as those illustrated in Deutsch, U.S. Pat. No. 2,375,286, Beachley, U.S. Pat. No. 2,358,437, Schaffner, U.S. Pat. No. 2,335,160, and Schaffner, U.S. Pat. No. 2,316,628.
Also, there are known and used spring structures that utilize simple coil and zigzag springs, but with these structures, comfort and durability are sacrificed.
Additional examples of structures that attempt to provide improved comfort and proper support are illustrated in Platt, U.S. Pat. No. 2,935,124 and Crites, U.S. Pat. No. 2,817,390.
All of the foregoing prior art patents attempt to provide at the lowest possible cost a spring structure that is sufficiently soft to be comfortable, but sufficiently stiff to provide proper support and prevent sag. There is therefore a need for an improved spring structure which can provide the soft and comfortable feel with proper support and without undesirable sag at a lower cost than the prior art structures.